Market researcher IHS-iSuppli said the iPad will continue to gain market share and spelled out the secrets of its success more than a year and a half after Apple introduced the groundbreaking product.

Steve Jobs--who resigned from Apple as CEO today--introduced the iPad in January of 2010 and its been a nonstop success ever since. Apple is set to increase shipments of the iPad "capitalizing on its shrewd strategy, as well as its competitors' stumbles," iSuppli said in a research note today. This alone will cause the global tablet market to expand.

Global media tablet shipments now are expected to rise to 60 million units in 2011, up 245.9 percent from 17.4 million in 2010, iSuppli said. This is an increase of a little more than a million from the previous iSuppli estimate. About half of this increase is based on the iPad, whose shipments should reach 44.2 million in 2011, up 500,000 units from the previous forecast.

Apple is expected to account for 74 percent of media tablet shipments in 2011, according to iSuppli.

"All the momentum in the media tablet market is with Apple right now," said Rhoda Alexander, an iSuppli analyst. "The competition can't seem to field a product with the right combination of hardware, marketing, applications and content to match up with the iPad," she wrote. On top of this, Apple's patent litigation is slowing competitors' entry into some key regional markets.

And what are the secrets of the iPad's success? These include "strong marketing and retail expansion not only in China but also other developing economies...[and] Apple is still the only tablet player truly benefiting from peripheral advertising, with content providers promoting their iPad-enabled content. The iPad also has profited from being the early favorite in the education space, a factor that will help to boost sales during the third-quarter back-to-school season," Alexander wrote.

In fact, the only real threat may come internally from the iPhone 5, which is expected to arrive this fall, Alexander said. And that is another key to the company's success. Much of Apple's most serious product competition comes from other Apple products.

The iPad 3 will keep the ball rolling in the first quarter of 2012 with the introduction of a high-resolution Retina display, iSuppli said. And Apple may "take a page from the iPhone handbook" and offer both the second- and third-generations of the iPad. "This would allow Apple to compete on price using the iPad 2--while simultaneously differentiating based on innovation with its new-generation product."